Evaluating the use of polarimetric cloud radars for studying winter storms
| dc.contributor.author | Long, David A., author | |
| dc.contributor.author | Rutledge, Steven A., author | |
| dc.date.accessioned | 2022-04-29T14:40:48Z | |
| dc.date.available | 2022-04-29T14:40:48Z | |
| dc.date.issued | 2004 | |
| dc.description | Spring 2004. | |
| dc.description | Also issued as David A. Long's thesis (M.S.) -- Colorado State University, 2004. | |
| dc.description.abstract | The purpose of this research was to model two Front Range snowstorms at millimeter wavelengths in order to evaluate the performance of the millimeter wavelengths concerning storm microphysics. Specifically, the question at what point, if any, do Mie scattering effects and attenuation become detrimental to further analysis is addressed. The T-matrix method was used to model the storms at Ku-band, Ka-band, and W-band: these wavelengths were chosen to simulate the Advanced Multi-Frequency Radar (AMFR), which is currently being developed by the University of Massachusetts in collaboration with CSU. The AMFR includes full polarimetric capability, so the modeled results include Zh as well as polarimetric quantities. The two snowstorms chosen were the March 2003 snowstorm and the October 1997 blizzard. Hydrometeor identification by means of fuzzy logic was used on the March 2003 snowstorm to extract microphysical information from the CHILL images to use as input for the T-matrix model. At 0600 UTC on 18 March 2003, the hydrometeor identification revealed a bright band east of about 30 km west of CHILL, where a barrier jet was located at the time. Snow was observed falling to the ground west of this boundary. At 0000 UTC on 19 March 2003, the storm was much more stratified, with snow falling everywhere in the radar domain. Modeled results for the earlier time indicate the oscillatory nature of the Mie regime when Zh for rain is examined, where Zh is 35.0 dBZ at S-band and 35.1 dBZ at Ku-band. The model output for a rain/snow mix was almost identical to that of rain alone, the dominant dielectric. For 0000 UTC on 19 March 2003, it was found that changing the density and particle size distributions of snow aggregates and crystals greatly affected the model output. Model output at both times displayed consistent trends such as low Zh ( due to Mie scattering) and higher attenuation at the shorter wavelengths. Microphysical information for the October 1997 blizzard was generated by the CSU-RAMS model, and this output was then used as input into T-matrix. Output (polarimetric radar quantities) was compared to CHILL images to verify the physical reality of the RAMS output. Output images from the T-matrix model indicated strong Mie effects at Ka-band and especially W-band. Zh was reduced to below 0 dBZ at W-band due to strong Mie scattering and path-dependent attenuation. The signal loss and oscillatory backscattering cross sections of the hydrometeors at W-band was detrimental to the interpretation of the other polarimetric quantities, and little physical interpretation could be done. It was concluded that Ku-band could be a useful observational wavelength, while Ka-band and W-band may not be useful in observing intense winter storms. | |
| dc.description.sponsorship | Sponsored by the National Science Foundation UM#02-522627. | |
| dc.format.medium | reports | |
| dc.identifier.uri | https://hdl.handle.net/10217/234890 | |
| dc.language | English | |
| dc.language.iso | eng | |
| dc.publisher | Colorado State University. Libraries | |
| dc.relation | Catalog record number (MMS ID): 991019749929703361 | |
| dc.relation | QC852 .C6 no. 748 | |
| dc.relation.ispartof | Atmospheric Science Papers (Blue Books) | |
| dc.relation.ispartof | Atmospheric science paper, no. 748 | |
| dc.rights | Copyright and other restrictions may apply. User is responsible for compliance with all applicable laws. For information about copyright law, please see https://libguides.colostate.edu/copyright. | |
| dc.subject | Winter storms -- United States | |
| dc.subject | Doppler radar | |
| dc.title | Evaluating the use of polarimetric cloud radars for studying winter storms | |
| dc.type | Text | |
| dcterms.rights.dpla | This Item is protected by copyright and/or related rights (https://rightsstatements.org/vocab/InC/1.0/). You are free to use this Item in any way that is permitted by the copyright and related rights legislation that applies to your use. For other uses you need to obtain permission from the rights-holder(s). |
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